Method of producing molded concrete products and apparatus therefor



March 19, 1940. w s, STRQNG 2,193,847

METHOD OF PRODUCING MOLDED CONCRETE PRODUCTS AND APPARATUS THEREFOR 7 Filed Dec 10, 1936 2 Sheets-Sheet 1 INVENTOR A WILLIAM E.S. STRONG March 19, 1940. w. E. s. STRONG METHOD OF PRODUCING IQLDED CONCRETE PRODUCTS AND APPARATUS THEREFOR Filed Dec. 10, 1956 2 Sheets-Sheet .2

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HQ El wnLLlAw m E5. STRONG HIS RNiY Patented Mar. 19, 1940 I PATENT. OFFICE METHOD OF irnonucmo MOLDED coN- CRETE PRODUCTS THEREFOR AND APPARATUS William E. S. Strong, New York, N. Y., assi'gnor to John B. Pierce Foundation, New York, N.'Y., a corporation of New York,

Application December 10, 1936, Serial No. 115,155

3 Claims.

This invention relates to a method of producing molded products from concrete or a like cementitious plastic material, and is particularly applicable to the production of units, such as wall slabs, floor slabs; roof slabs, etc. for use,

primarily, in buildingconstruction. The invention relates also to apparatus for accomplishing the method.

Building units, preferably of concrete. resulting from the practice of the method are charac-' terized by an entire superficial area substantially surface finished, by an' exceedingly dense homogeneous surface structure at the particular faces intended for exposure'to weathering or wear. by a solid and closely knit body structure throughout, and by strength exceeding that of other types of cast or so called vibrated concrete.

The method of the invention involves, fundamentally, jarring of the concrete simultaneouslv with compression thereof within an enclosing forming chamber, whereby the desired physical characteristics are imparted to the resulting product. An important step of the method resides in the conducting of alimited quantity of the plastic cementitious material from confinement during the molding thereof.

According to preferred practice. a mold-box for retaining a charge of the plastic concrete is so utilized as one part 01 the mold, the charge of concrete being preferably placed in the mold-box according to the general configuration of the resuiting product. A forming cover is provided for the moldbox for function as the other part 'of the mold, and is positioned under pressure over the charge of concrete while the mold-box is being jarred, preferably in a substantially vertical plane, provision being made for the escape of surplus concrete from the confines of the cooperating mold-box and forming cover. It

should be noted that the charge of plastic concrete is, in material content, sufficiently grea er than the material content of the resulting molded product to insure complete'filling of the molding enclosure formed bythe mold box'and the coopcrating forming cover. The provision for escape of surplus plastic concrete during the molding process permits .of the use of this charge of ex cessive material content. 1

After sumcient time has elapsed for the plastic concrete to adapt itself to the exact configuration of the mold and to obtain the desired physical treatment, usually the time period re- I quired is not more than a couple of minutes, the la. jarring action-on the mold-box-and the pressure on the forming cover are stopped, and the forming cover is removed from the mold-box.

Because of the combined jarring action and compression, all air between the form surfaces I of the mold and the plastic concrete is normally driven out, resulting in the creation of a vacuum seal thereat. According to one phase of the in- .vention provision is made for breaking the vacuum seal. This is preferably accomplished by the introduction of compressed air between the surfaces concerned.

While the present method is hereinafter described and claimed with particular emphasis-on concrete as the material operated upon. it is clearly within the scope of this invention to operate upon any plastic material if advantages are to behad thereby.

In the drawings:

Fig. 1 illustrates, in front elevation a preferred embodiment of apparatus for practicing the present method according to an advantageous pro- 'cedure.

cover are illustrated in vertical section taken adjacent the nearer end;

. Fig. 2 represents. an enlarged detail view of the mold assembly as illustrated in Fig. 1, at the completion of a, molding operation and 'just prior to removal of the forming cover from the molded product. One embodiment of means for breaking the vacuumseal is particularly illustrated; I

Fig. 3 is a view corresponding to Fig. 2 but illustrating the molded product after removal of the forming cover;

Fig. 4 illustrates in perspective a type of building unit produced by the apparatus of the prior figures; 1

The moldbox assembly and forming Fig. 5 represents an enlarged fragmentary detail in vertical section of another embodiment of means for controlling introduction of compressed air for breaking the vacuum seal.

Referring to the drawings: at ill, see especially 'Fig. l, is illustrated a mold-box ofany suitable means, not shown,) to a box-frame I 2 rigidly secured at its comers to respective bufier blocks l3. The mold-box assembly rests on respective foundation piers I 4, rising from a floor or other supporting structure l5 and serving to support the box-frame l2 at its corners through the medium of respective bufler blocks I 6 cooperating with the respective buffer blocks l 3. Guide plates bearing standards and buffer blocks provide in effect, a base for'the mounting of the mold blocks. The respective spiral cams l8 coopefate with respective rollers 2| journaled in respective brackets 22 which depend rigidly from the underside of box-frame l2. There is preferably a spiral cam l8 and cooperating roller 2| located adjacent each of the sets of buffer blocks [3 and I6 for throughout the extent of the mold-box.

The shafts IQ and 20, respectively, may be rotated by means of a shaft 23 extending latitudinally between the first mentioned shafts, and engaging therewith; the engagement being had by means of miter gears 23a and 23b rigidly carried by the ends of shaft 23, meshing, respectively, with the mitergears lfla and 20a carried by ends of the shafts i9 and 23, respectively. The shaft 23 may be journaled in the bearing standards 24 and 25, and may be actuated by any suitable means such as the electric motor 26 connected therewith by the flexible belting, as indicated generally at 2'5.

Rotation of the shaft 23 by the motor effects rotation of the longitudinal shafts it! and 20 and therewith the cams it. The cams serve to alternately'raise and let drop freely the moldbox M. The downstroke of the reciprocation, represented by the alternate raising and free drop of the mold-box I ii, is halted abruptly when the respective buffer blocks i3 and i6 meet. The reciprocation may be of any suitable frequency; between 400 and 600 strokes per minute is preferred for best practical results.

A forming cover, indicated generally at 36, is provided for cooperation with the mold-box it] during the molding operation. The forming cover 36 may comprise a form plate 3i having its form surfaces die conflgurated according to the configuration desired for the molded product. In the present case the form plate 3! is provided with recesses on its'upper surface and is secured to a cover plate 32 in an air-tight manner to produce sealed chambers 30a and 30b, utilized as hereinafter disclosed in connection with the breaking of the vacuum seal between the form surfaces and the yet plastic concrete.

For support of the forming cover 30, the supporting rods 33, depending from the ends of an X shaped floating frame 34, are slidably and adjustably secured in cars 32a, extending rigidly from near the corners of cover plate 32, by means of the nuts 35 cooperating with threaded ends of the stated supporting rods.

The floating frame 34 is mounted for up and down movement in a carriage 36, the supporting affording uniformity of jarring action rods 33 passing through the sleeves 38-! in sliding relationship therewith. The carriage 33 may be mounted for horizontal movement on the rails 31 of a stationary track structure 38 by means of the wheels 39.

A cylinder, indicated generally at 40, is rigidly mounted centrally of the carriage 36 as by means of the leg members 4|. A piston 42, operable in the cylinder 40, is rigidly secured at its end to the midpoint of the floating frame 34; its operation within the cylinder 40 is controlled by compressed air admitted through the piping 43. Movement of the piston 42 effects up and down movement of the forming cover 30 relative to the mold-box l0. 4

The supporting rods 33 have adjustably secured thereon the nut assemblies 44 spaced apart from the nuts 35 sufliciently to allow the reception of coil springs 45 therebetween. Such coil springs serve to absorb the shock of the jarring action transmitted from the mold-box. Adjustment of the respective nuts 35 or 44 determines the degree of compression of the coil springs 45.

The piston 42, during its down stroke, exerts a constantly advancing pressure on the forming cover; the transmission of the pressure through the coil springs is such, however, as to absorb the jarring action of the mold-box as the forming cover is placed.

For carrying out the desired molding operation, the carriage 36 is positioned directly above the mold-box l0, and suitable control of admission of air to the cylinder 40 is' effected to lower the forming cover 30 to placement over the mold-box. When the forming cover 30 is approximately in final placement, jarring action of the mold-box is'effected through the mechanism afore described. Pressure of the forming cover into final placement is accomplished simultaneously with the jarring of the mold-box, thus insuring positive flow of the plastic concrete into full conformity with the mold, and the attainment of desired physical characteristics for the molded concrete.

For conducting surplus concrete from the confines of the mold during the molding operation, holes 46 may be provided at appropriately spaced locations along the length of the forming cover 36, note particularly Fig. 2.

The simultaneous jarring and compression of the plastic concrete in the mold normally produces a vacuum seal between the form surfaces of the form plate 3i and the yet plastic, molded product. To remove the forming cover without damage to the yet plastic product, it is necessary that the vacuum seal be broken.

For accomplishing break of the vacuum seal, compressed air is advantageously introduced between the surfacm concerned before removal of the forming cover of the mold.

A preferred type of mechanism for accomplishing introduction of compressed air as afore described is illustrated in Figs. 1 and 2.

A control-valve cylinder 48 is mounted on the cover plate 32 and is provided at its ends with the air supply piping indicated at 43 and 50, for the admission of compressed air to the interior of the cylinder. Areciprocating piston 5| having the rack ends Sid and Ilb extending from the cylinder and engaging the pinions 52 and 53 respectively, is mounted for reciprocation in the cylinder 48. Passage of air from the controlvalve cylinder 48, intermediate its ends, into the sealed chambers 30a and 30b is provided for by 75.

' spaced locations in the walls of, the form plate 3|, communicating with the sealed chambers 30a and 30b of the forming cover 30 and opening at the form surfaces of the form plate.

Adapted to cooperate with the passages 3ll are closure plugs 55 mounted at suitable spaced locations on the carriers 56 and 51 respectively.

- the vacuum seal therebetween. Hence, the formmg cover may be lifted from operative position on the mold-box Ill without damage to the molded product represented at H, Figs. 3 and 4.

During the actual molding operation the passages 41 are closed tightly by the closure plugs 55, precluding entry of plastic concrete to the sealed chambers 30a and 30b.

Another embodiment of means for introducing air between the form surfaces of the forming plate 3| and the yet plastic, molded concrete is illustrated fragmentarily in Fig. 5. Any wellknown valve means maybe substituted for the valve cylinder 48 in controlling admission of air through the piping 60, into the sealed chambers 30a and 30b. The passage of air to the desired locations between the aforementioned surfaces for breaking the vacuum seal thereat, is accomplished by means of check valves positioned at spaced locations along the bottom walls of the forming plate 3|.

Each check valve may comprise a machine screw 6| having its head Gla. fitted snugly into the passage 62 between the particular sealed chambers 30a or 30b concerned andthe form surfaces of the plate 3|, and having its screw-end threaded into a plate 63 slidably mounted upon the guide rods 64 and '65. A cofl spring 66 interposed between the plate 63 and the lower wallof the form plate 3| insures positive closure-of the passage 62 during the molding operation.

When the forming cover is to be removed from the yet plastic, molded product, compressed air admitted through the piping 60 depresses the plate 63 and effects opening of the passage 62, for accomplishing breaking of the vacuum seal.

The entire molding operation inclusive of preper filling of the mold-box l0, simultaneous jarring and compression of the plastic concrete ll, break rapid production of molded concrete building units.

- Whereas this invention has been described with respect to preferred practice of the method and preferred embodiments of the apparatus, it is to be distinctly understood that many changes may be made from time to time as the art progresses without departing from the spirit of the invention as defined in the following claims.

I claim:

1. A method of producing molded products of substantially slab formation with projections extending from a face thereof which comprises, filling an open mold-box, according to the general configuration of the said face, with a mass of plastic cementitious material whose material content is greater than the material content of the resulting product; closing the said open moldbox with a forming cover which is die configurated on its-underside to form the desired projections of the said face of the product, and simultaneously jarring the mold-box in strokes alternately toward and away from the said forming cover; conducting the surplus plastic cementitious material from the mold-box during placement of said forming cover; and limiting theplacement of said forming cover to a predetermined closing position with respect to said mold-box.

2. A method of forming molded products from plastic cementitious material comprising confining the material to be molded on all sides except the top; subjecting thetop of the said material to. the pressure of a descending forming element,

and simultaneously jarring the said material;-

conducting a limited quantity of the said maincluding in combination, an open mold-box; a

mounting for said mold-box comprising a base,

and a plurality of cams spaced apart and rotatably mounted on said base in such manner as to support the said mold-box substantially symmetrically about its periphery, said cams being operable alternately to raise the mold-box substantially vertically from the said base and to let it freely drop back thereonto; a forming cover for said mold-box, said forming cover being adapted to rest upon the walls of said mold-box for resisting pressure toward the interior thereof mechanical means for exerting a constantly advancing pressure on said forming cover during placement thereof on said mold-box; spring elements connecting said mechanical means with said forming cover at spaced locations thereof substantially coinciding with the locations of said cams; openings through said forming cover affording passage for outward flow of surplus material from within the confines of said moldbox and said forming cover during placement of the latter; and means for rotating said cams. 

